Tokyo Institute of TechnologyJAPANESE

Research

Wireless transceivers for future 6G small satellite constellation

We are currently conducting research and developing wireless transceivers and integrated circuits for wireless communications that can operate in space to realize low earth orbit small satellite constellation, which is expected to be a future 6G communication network. The key to realizing such a network is to reduce the size and weight of the radio equipment mounted on the satellite, make it highly radiation tolerant, and reduce its power consumption. In 2022, we plan to launch JAXA's Innovative Satellite Technology Demonstration-3 into a 560km low earth orbit.

The study of space deployable membrane phased array radios consists of a phased array radio on a large deployable membrane surface, which is folded small at launch to realize a large-area antenna after orbit insertion to enable high-speed wireless communications. This research will allow non-planarity of the membrane surface after deployment and compensate for the non-planarity of the array by the amplitude and phase of each antenna element, thereby dramatically reducing size and weight. So far, we have created a non-planar phased-array transceiver operating in the Ka-band, demonstrated the effectiveness of the compensation technique, and plan to conduct a space demonstration in 2022.

Concept of small satellite constellation for future 6G networks
Concept of small satellite constellation for future 6G networks
Left figure: space deployable non-planar phased-array transceiver. Right figure: non-planar phased-array transceiver board (plan to launch in 2022)
Left figure: space deployable non-planar phased-array transceiver. Right figure: non-planar phased-array transceiver board (plan to launch in 2022)

Radiation-hardened RF integrated circuits

Our research on highly radiation-tolerant RF ICs aims to realize radios that can operate for long periods even in the harsh environment of space. Radiation in the space environment gradually degrades RF ICs, causing problems in their functionality. The RF IC designed by this laboratory has achieved radiation tolerance dozens of times higher than that of conventional RF ICs and has succeeded in significantly extending the orbital life of radio equipment. In addition, to enable operation with the limited power resources of small satellites, the power consumption of the RF ICs is less than one-tenth that of commercially available radio ICs. Through research and development of such core technologies as high radiation tolerance and low power consumption of RF ICs, we will pioneer the evolution of wireless communications deployed in space in the future.

Radiation hardened & ultra-low-power Ka-band RF  IC and phased-array transceiver for small satellite
Radiation hardened & ultra-low-power Ka-band RF IC and phased-array transceiver for small satellite

Battery-free millimeter wave 5G relay wireless transceiver

To date, this laboratory has successfully developed a millimeter-wave band 5G relay transceiver that can operate without the need for a power supply. This transceiver uses wireless power transfer technology to eliminate the need for a power source, and relays and beamforms 28 GHz band radio waves to enable millimeter-wave band 5G communications even in areas where radio waves have not been able to reach so far. Conventionally, millimeter-wave band 5G phased arrays for beamforming have consumed several hundred milliwatts of power per antenna element, making it difficult to operate with the power generated by wireless power transfer. Using a newly proposed vector summing backscattering technique, this research successfully achieved beamforming with a power consumption of 30 microwatts per element, more than three orders of magnitude less. The wireless transceiver was realized using an inexpensive, mass-producible silicon CMOS process IC, and has succeeded in wireless power transfer in the 24 GHz band and 5G-compliant wireless communications in the 28 GHz band.

Concept of battery-free millimeter-wave 5G relay  transceiver using wireless power transfer
Concept of battery-free millimeter-wave 5G relay transceiver using wireless power transfer
Fabricated 5G phased-array relay transceiver with wireless power and LO transfer
Fabricated 5G phased-array relay transceiver with wireless power and LO transfer